Freshman year is when you step up academically from middle school, and have the most freedom to explore multiple extracurriculars.
As I have written elsewhere, grades and rigor are the foundation for applying to highly selective colleges. Your goal this year is to develop the study habits and discipline needed to get good grades but still have time for extracurriculars. Hopefully you are already taking a highly rigorous courseload, but if not, grades become even more important so you can step up in rigor next year.
During classes, you should practice becoming the type of student that teachers love. Do that starting in freshman year, and it will become automatic by junior year, allowing you to earn great recommendations.
In terms of extracurriculars, it’s fine to have several different interests, but by the end of freshman year you should find one or two activities that you are deeply interested in. You will continue to develop those deep interests until it becomes an area of exceptional talent (i.e. a “spike”An exceptional talent in an academic or extracurricular area... More) that you highlight in your college applications.
The ideal time to further develop one of those interests is during summer after freshman year. Starting in December, start looking for summer camps or jobs that align with your main interests. For example, if your primary interest is in history, look for camps that explore the history of a particular civilization. If it is neuroscience, consider a class on genetics.
